silanisation

Silanisation is a chemical process used to modify the surface of materials, typically glass, silica, or metal oxides. It involves the reaction of a silane coupling agent with hydroxyl groups present on the surface. Silane coupling agents are molecules that possess at least one alkoxysilyl group, which can react with these surface hydroxyls, and at least one organofunctional group, which can interact with or bond to an organic material. This dual functionality allows for the creation of a stable interface between inorganic and organic phases.

The reaction typically occurs in the presence of a solvent, often water, which hydrolyzes the alkoxysilyl groups to reactive silanol groups. These silanol groups then condense with the hydroxyl groups on the substrate surface, forming strong covalent bonds, often siloxane bonds. Further condensation can occur between adjacent silanol groups, forming a cross-linked polysiloxane layer. The organofunctional group on the silane molecule remains available for subsequent reactions or interactions with organic polymers, coatings, or adhesives.

Silanisation is widely employed to improve adhesion between dissimilar materials. For example, it is used to enhance the bond strength between glass fibers and polymer matrices in composites, to improve the durability of coatings on glass, and to functionalize silica surfaces for chromatography or biomedical applications. The specific silane coupling agent chosen depends on the nature of the substrate and the organic material it needs to interact with. Different organofunctional groups, such as amino, epoxy, methacryloxy, or vinyl groups, can be incorporated to achieve specific properties and compatibilities.